A hard wood floor over a separating structure is an impact-sound problem waiting to happen. In apartments, conversions and any project covered by Approved Document E, footfall transmitted to the room below is exactly what the regulations are written to control, and it is the line that most often catches an engineered-wood specification late. The good news is that it is a build-up problem with a build-up solution.
What Part E actually asks for
Approved Document E sets performance standards for airborne and impact sound insulation between dwellings, verified on site by pre-completion testing (or by registering a Robust Detail). For floors, impact sound, the weighted normalised impact sound pressure level, L’nT,w, is the figure a hard floor finish most affects. A bare engineered-wood floor bonded to a screed offers little impact isolation on its own; the resilient layer underneath is what does the work.
Silent Lay+, the resilient layer for wood floors
Silent Lay+ is the acoustic underlayment we specify under engineered wood, available from us in 2 mm and 3 mm. It is a homogeneous mat of agglomerated cork and recycled SBR rubber bonded with a polyurethane elastomer, durable, low residual indentation, and free from plasticiser migration. It installs with both glued and floating wood build-ups.
The tested numbers
From the Silent Lay+ technical data sheet, the published acoustic improvement is a tested impact-sound improvement (ISO 16251) of 18 dB at 2 mm and 17 dB at 3 mm, with an ASTM ΔIIC of 23–25 across those build-ups (note: those acoustic tests were run on a resilient floating LVT assembly; for a specific engineered-wood floor the assembly should be tested to confirm its on-site L’nT,w). Mechanically, to EN 16354 the wood-grade product gives compressive strength >200 kPa (2 mm) and a low thermal resistance of 0.030–0.039 m²·°C/W, so it stays compatible with underfloor heating.
How to use it in a Part E specification
Treat Silent Lay+ as the impact-isolation layer within a tested floor build-up rather than a stand-alone “Part E pass”: specify the underlay thickness, confirm the full assembly by pre-completion test or Robust Detail, and keep the substrate level, dry (≤ 2.5% MC) and clean per the TDS. Used this way, it lets an engineered oak floor go into apartments and conversions without acoustic risk, and the recycled-rubber-and-cork make-up adds a small circularity credit to the spec.
Download the Silent Lay+ technical data sheet (PDF)